Influence of Machine Type and Powder Batch During Laser-Based Powder Bed Fusion (L-PBF) of AISI 316L

2021 ◽  
Author(s):  
Sebastian Greco ◽  
Kevin Gutzeit ◽  
Hendrik Hotz ◽  
Marc Schmidt ◽  
Marco Zimmermann ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Scanning Speed ◽  
Industrial Applications ◽  
Raw Material ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Aisi 316L ◽  
Powder Bed ◽  
Machine Type ◽  
Microhardness And Microstructure

Abstract The use of additive manufacturing (AM) in industrial applications is steadily increasing due to its near net shape production and high design-freedom. For metallic components, laser-based powder bed fusion (L-PBF) is currently one of the most widely used AM processes. During L-PBF, a component is manufactured layer by layer from a powdery raw material. The process is controlled by a multitude of parameters like the laser power, scanning speed and layer thickness, whose combination significantly influences the properties of the components. In this study, the influence of the L-PBF machine type and the influence of the powder batch are investigated by means of relative density, microhardness and microstructure of the components. For this purpose, three setups are defined, differing in the powder batch and machine type used. By comparing the process results of the additive manufacturing of different setups, the influence of the machine type and powder batch are determined. The considered material is stainless steel AISI 316L. The results revealed significant differences between all investigated properties of the additively manufactured components. Consequently, process parameter combinations cannot be transferred between different machine types and powder batches without verification of the component properties and, if necessary, special adaption of the process.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

Additive Manufacturing of Nickel-Based Super Alloys for Aero Engine Applications

2020 ◽  
pp. 48-70
Author(s):  
Raja A. ◽  
Mythreyi O. V. ◽  
Jayaganthan R.
Keyword(s):  
Additive Manufacturing ◽  
Complex Geometry ◽  
Source Parameters ◽  
Raw Material ◽  
Layer By Layer ◽  
Powder Bed ◽  
Complex Design ◽  
Direct Energy ◽  
Second Phases ◽  
Metal Addition

Ni based super alloys are widely used in engine turbines because of their proven performance at high temperatures. Manufacturing these parts by additive manufacturing (AM) methods provides researchers a lot of creative space for complex design to improve efficiency. Powder bed fusion (PBF) and direct energy deposition (DED) are the two most widely-used metal AM methods. Both methods are influenced by the source, parameters, design, and raw material. Selective laser melting is one of the laser-based PBF techniques to create small layer thickness and complex geometry with greater accuracy and properties. The layer-by-layer metal addition generates epitaxial growth and solidification in the built direction. There are different second phases in the Ni-based superalloys. This chapter details the micro-segregation of these particles and its influence on the microstructure, and mechanical properties are dependent on the process influencing parameters, the thermal kinetics during the process, and the post-processing treatments.

scholarly journals Influence of Ring-Shaped Beam Profiles on Process Stability and Productivity in Laser-Based Powder Bed Fusion of AISI 316L

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1989
Author(s):  
Jonas Grünewald ◽  
Florian Gehringer ◽  
Maximilian Schmöller ◽  
Katrin Wudy
Keyword(s):  
Laser Power ◽  
Scanning Speed ◽  
Process Window ◽  
Powder Bed Fusion ◽  
Aisi 316L ◽  
Process Stability ◽  
Cross Sectional ◽  
Powder Bed ◽  
Shaped Beam ◽  
Process Robustness

A major factor slowing down the establishment of additive manufacturing processes as production processes is insufficient reproducibility and productivity. Therefore, this work investigates the influence of ring-shaped beam profiles on process stability and productivity in laser-based powder bed fusion of AISI 316L. For this purpose, the weld track geometries of single tracks and multi-track segments with varying laser power, scan speed, hatch distance, and beam profile (Gaussian profile and three different ring-shaped profiles) are analyzed. To evaluate the process robustness, process windows are identified by classifying the generated single tracks into different process categories. The influence of the beam profiles on productivity is studied by analyzing the molten cross-sectional areas and volumes per time. When using ring-shaped beam profiles, the process windows are significantly larger (up to a laser power of 1050 W and a scanning speed of 1700 mm/s) than those of Gaussian beams (laser power up to 450 W and scanning speed up to 1100 mm/s), which suggests a higher process robustness and stability. With ring-shaped beam profiles, larger volumes can be stably melted per track and time. The weld tracks created with ring-shaped profiles are significantly wider than those generated with Gaussian profiles (up to factor 2 within the process window), allowing enlargement of the hatch distances. Due to the higher scanning speeds and the enlarged hatch distances for ring-shaped beam profiles, the process can be accelerated by a factor of approximately 2 in the parameter range investigated.

scholarly journals Qualification of a Ni–Cu Alloy for the Laser Powder Bed Fusion Process (LPBF): Its Microstructure and Mechanical Properties

2020 ◽  
Vol 10 (10) ◽  
pp. 3401 ◽  
Author(s):  
Iris Raffeis ◽  
Frank Adjei-Kyeremeh ◽  
Uwe Vroomen ◽  
Elmar Westhoff ◽  
Sebastian Bremen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Scanning Speed ◽  
Tensile Tests ◽  
Industrial Applications ◽  
Fusion Process ◽  
Material Base ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Significant Difference

As researchers continue to seek the expansion of the material base for additive manufacturing, there is a need to focus attention on the Ni–Cu group of alloys which conventionally has wide industrial applications. In this work, the G-NiCu30Nb casting alloy, a variant of the Monel family of alloys with Nb and high Si content is, for the first time, processed via the laser powder bed fusion process (LPBF). Being novel to the LPBF processes, optimum LPBF parameters were determined, and hardness and tensile tests were performed in as-built conditions and after heat treatment at 1000 °C. Microstructures of the as-cast and the as-built condition were compared. Highly dense samples (99.8% density) were achieved after varying hatch distance (80 µm and 140 µm) with scanning speed (550 mm/s–1500 mm/s). There was no significant difference in microhardness between varied hatch distance print sets. Microhardness of the as-built condition (247 HV0.2) exceeded the as-cast microhardness (179 HV0.2.). Tensile specimens built in vertical (V) and horizontal (H) orientations revealed degrees of anisotropy and were superior to conventionally reported figures. Post heat treatment increased ductility from 20% to 31% (V), as well as from 16% to 25% (H), while ultimate tensile strength (UTS) and yield strength (YS) were considerably reduced.

scholarly journals Micro milling of additively manufactured AISI 316L: impact of the layerwise microstructure on the process results

2020 ◽  
Vol 112 (1-2) ◽  
pp. 361-373
Author(s):  
Sebastian Greco ◽  
Sonja Kieren-Ehses ◽  
Benjamin Kirsch ◽  
Jan C. Aurich
Keyword(s):  
Additive Manufacturing ◽  
Laser Scanning ◽  
Scanning Speed ◽  
Micro Milling ◽  
Burr Formation ◽  
Layer By Layer ◽  
Aisi 316L ◽  
Building Components ◽  
Laser Scanning Speed ◽  
The Impact

AbstractIn the field of metal additive manufacturing (AM), one of the most used methods is selective laser melting (SLM)—building components layer by layer in a powder bed via laser. The process of SLM is defined by several parameters like laser power, laser scanning speed, hatch spacing, or layer thickness. The manufacturing of small components via AM is very difficult as it sets high demands on the powder to be used and on the SLM process in general. Hence, SLM with subsequent micromilling is a suitable method for the production of microstructured, additively manufactured components. One application for this kind of components is microstructured implants which are typically unique and therefore well suited for additive manufacturing. In order to enable the micromachining of additively manufactured materials, the influence of the special properties of the additive manufactured material on micromilling processes needs to be investigated. In this research, a detailed characterization of additive manufactured workpieces made of AISI 316L is shown. Further, the impact of the process parameters and the build-up direction defined during SLM on the workpiece properties is investigated. The resulting impact of the workpiece properties on micromilling is analyzed and rated on the basis of process forces, burr formation, surface roughness, and tool wear. Significant differences in the results of micromilling were found depending on the geometry of the melt paths generated during SLM.

scholarly journals Additive Manufacturing of Polypropylene: a Screening Design of Experiment Using Laser-Based Powder Bed Fusion

2018 ◽  
Author(s):  
Inigo Flores Ituarte ◽  
Olli Wiikinkoski ◽  
Anton Jansson
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Design Of Experiment ◽  
Manufacturing Industry ◽  
Tensile Elongation ◽  
Scanning Speed ◽  
Process Window ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
The Impact

The use of commodity polymers such as polypropylene (PP) is key to open new market segments and applications for the additive manufacturing industry. Technologies such as powder-bed fusion (PBF) can process PP powder; however, much is still to learn concerning process parameters for reliable manufacturing. This study focusses in the process-property relationships of PP using laser-based PBF. The research presents an overview of the intrinsic and the extrinsic characteristic of a commercial PP powder as well as fabrication of tensile specimens with varying process parameters to characterize tensile, elongation at break, and porosity properties. The impact of key process parameters, such as power and scanning speed are systematically modified in a controlled design of experiment. The results were compared to the existing body of knowledge; the outcome is to present a process window and optimal process parameters for industrial use of PP. The computer tomography data revealed a highly porous structure inside specimens ranging between 8.46% and 10.08%, with porosity concentrated in the interlayer planes in the build direction. The results of the design of experiment for this commercial material show a narrow window of 0.122 ≥ Ev ≥ 0.138 J/mm3 led to increased mechanical properties while maintaining geometrical stability.

scholarly journals Spreading of Powders in Powder Bed Additive Manufacturing: an Experimental Approach

2021 ◽  
Author(s):  
Valerio Lampitella ◽  
Marco Trofa ◽  
Antonello Astarita ◽  
Gaetano D’Avino
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Process Parameters ◽  
Experimental Approach ◽  
Physical Mechanism ◽  
Industrial Applications ◽  
Powder Bed Fusion ◽  
Spreading Process ◽  
Powder Bed ◽  
Optimal Window

Powder bed additive manufacturing allows for the production of fully customizable parts and is of great interest for industrial applications. However, the repeatability of the parts and the uniformity of the mechanical properties are still an issue. More specifically, the physical mechanism of the spreading process of the powders, which significantly affects the characteristics of the final part, is not completely understood. In powder bed fusion technologies, the spreading is performed by a device, typically a roller or a blade, that collects the powders from the feedstock and successively deposits them in a layer of several dozens of microns that is then processed with a laser beam. In this work, an experimental approach is developed and employed to study the powder spreading process and analyze in detail the motion of the powders from the accumulation zone to the deposition stage. The presented experiments are carried out on a home-made device that reproduces the spreading process and enables the measurement of the characteristics of the powder bed. Furthermore, the correlation with the process parameters, e.g., the speed of the spreading device, is also investigated. These results can be used to obtain useful insights on the optimal window for the process parameters.

scholarly journals Additive Manufacturing of Polypropylene: A Screening Design of Experiment Using Laser-Based Powder Bed Fusion

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1293 ◽  
Author(s):  
Iñigo Flores Ituarte ◽  
Olli Wiikinkoski ◽  
Anton Jansson
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Design Of Experiment ◽  
Manufacturing Industry ◽  
Tensile Elongation ◽  
Scanning Speed ◽  
Process Window ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
The Impact

The use of commodity polymers such as polypropylene (PP) is key to open new market segments and applications for the additive manufacturing industry. Technologies such as powder-bed fusion (PBF) can process PP powder; however, much is still to learn concerning process parameters for reliable manufacturing. This study focusses in the process–property relationships of PP using laser-based PBF. The research presents an overview of the intrinsic and the extrinsic characteristic of a commercial PP powder as well as fabrication of tensile specimens with varying process parameters to characterize tensile, elongation at break, and porosity properties. The impact of key process parameters, such as power and scanning speed, are systematically modified in a controlled design of experiment. The results were compared to the existing body of knowledge; the outcome is to present a process window and optimal process parameters for industrial use of PP. The computer tomography data revealed a highly porous structure inside specimens ranging between 8.46% and 10.08%, with porosity concentrated in the interlayer planes in the build direction. The results of the design of experiment for this commercial material show a narrow window of 0.122 ≥ Ev ≥ 0.138 J/mm3 led to increased mechanical properties while maintaining geometrical stability.

Investigation of mechanical properties and microstructures of GH536 fabricated by laser powder bed fusion additive manufacturing

2020 ◽  
Vol 235 (1-2) ◽  
pp. 155-165
Author(s):  
Yunpeng Ren ◽  
Heng Lu ◽  
Dongyang Xu ◽  
Yan Chen ◽  
Zhiduo Xin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Relative Density ◽  
Laser Energy ◽  
Hot Forging ◽  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Laser powder bed fusion additive manufacturing of superalloys has received increasing attention in these years. In this article, the influence of parameters of laser powder bed fusion on mechanical properties and microstructures of nickel-based superalloy GH536 was investigated. Influence of laser power, scanning speed, hatch space and building direction on mechanical properties was discussed, and the optimal parameters were obtained. The relative density of samples fabricated by laser powder bed fusion could be as high as 99.5%. The processing window of laser energy density with 8.56 × 104–1.15 × 105 J/cm3 should be employed to make sure that the relative density is higher than 98%. The ultimate tensile strength and yield stress of GH536 sample made by laser powder bed fusion were 950 and 606 MPa, respectively, which were superior to samples with the tensile strength of 767 MPa and yield strength of 379 MPa prepared by traditional hot forging method. The hardness of the sample could reach 316.8 HV.

scholarly journals Influence of Microstructure and Defects on Mechanical Properties of AISI H13 Manufactured by Electron Beam Powder Bed Fusion

2021 ◽  
Author(s):  
Moritz Kahlert ◽  
Florian Brenne ◽  
Malte Vollmer ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Internal Cooling ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Fine Grained ◽  
Aisi H13

AbstractElectron beam powder bed fusion (E-PBF) is a well-known additive manufacturing process. Components are realized based on layer-by-layer melting of metal powder. Due to the high degree of design freedom, additive manufacturing came into focus of tooling industry, especially for tools with sophisticated internal cooling channels. The present work focuses on the relationships between processing, microstructure evolution, chemical composition and mechanical properties of a high alloyed tool steel AISI H13 (1.2344, X40CrMoV5-1) processed by E-PBF. The specimens are free of cracks, however, lack of fusion defects are found upon use of non-optimized parameters finally affecting the mechanical properties detrimentally. Specimens built based on suitable parameters show a relatively fine grained bainitic/martensitic microstructure, finally resulting in a high ultimate strength and an even slightly higher failure strain compared to conventionally processed and heat treated AISI H13.

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